The present invention relates to an apparatus for analyzing a liquid sample such as a biological sample, and more particularly to an analyzing apparatus having a pipetting device for transferring a sample from a sample cup to a reaction vessel.
In an automated analyzing apparatus for analyzing many kinds of analytical items by reacting a biological sample with reagents, an analyzing apparatus is widely employed of a type in which a row of reaction vessels are transferred with a turntable, as disclosed in, for example, Japanese Patent Publication No.6-27743 (1994) and Japanese Patent Application Laid-Open No.6-88828 (1994).
Japanese Patent Application Laid-Open No.6-88828 (1994) teaches an immunoassay apparatus which comprises a reagent unit having a turntable arranging reagent bottles, a sample transfer unit for transferring a sample rack to a sample pipetting position on the transfer path, a reagent delivery unit for delivering reagents from the reagent unit to a reaction table, and a sample delivery unit for deliver a sample from the sample rack to the reaction table.
On the other hand, a sample delivery apparatus without turntable is disclosed in Japanese Patent Application Laid-Open No.4-296655 (1992). In this conventional technology, test tubes which are empty, sample cups and nozzle tips are arranged on an X-Y stage, and the disposable nozzle tip is connected to a nozzle communicated with a pump, to deliver the sample cup to the test tube.
The inventors of the present invention have tried to realize an automated analyzing apparatus using disposable nozzle tips and disposable reaction vessels. However, when the method of delivering a tip as in Japanese Patent Application Laid-Open No.4-296655 (1992) is employed in this analyzing apparatus, it is necessary to connect the tip to the nozzle on the tip array region on the X-Y stage.
In this case, since a pushing force is applied against the tip rack when the tip is connected to the nozzle, the tip rack needs to have a strong structure. If an operator of the analyzing apparatus reuses the tip rack, many tips on the tip rack must be arranged by hand. On the other hand, if a tip rack having a strong structure is used, extra cost is required.